Yup, you don't outgrow it. Good for you that you investigated the issues of inattentiveness instead of jumping to the conclusion of ADHD. Kids can have both but if they only have APD, then ADHD medication won't help.
The Sound of Hope is a good resource. Rosie O'Donnel's son has APD:
This is a list of possible accommodations for kids with APD from understood.org:
https://www.understood.org/en/school-learning/partnering-with-childs-school/instructional-strategies/classroom-accommodations-for-auditory-processing-disorder
If your kid is in pubic school, you'll probably need to submit an IEP request in writing and allow them to test your kid independently. They may or may not accept the findings of outside testing. If this process yields inadequate supports, you may want to consider hiring an advocate to help you in the IEP process.